322 - Bone health for life: building strong bones, preventing age-related loss, osteoporosis, & more

KEYPOINTS

• 01

  Bone adapts to mechanical loading—its structure literally aligns with force.

  Beck, an Australian bone researcher, notes that in 1882 scientists described trabecular struts aligning with the forces placed on them. Bone is a 'use it or lose it' tissue: it needs brief, high-magnitude loading, not endurance—'you don't need to run a marathon, just one sprint' to stimulate bone cells.

• 02

  Peak bone mass is built in childhood and adolescence, and then it's a glider.

  The growth spurt comes around 12 in girls and 13–14 in boys; bone accrual ends around 18 in girls and as late as 25 in boys when growth plates fuse, with most people done by 30. Peter's glider analogy: you reach maximum altitude about 20 years into life, and afterward the best you can do is slow the descent. Genetics explain an estimated 70–80% of bone density, per twin studies, so family history matters.

• 03

  Women start with less bone and lose it faster, especially after menopause.

  In their 20s women have less bone than men, and at menopause (average around 52–54) circulating estrogen nearly vanishes, accelerating loss for perhaps 5–8 years. By late life the gap is substantial.

• 04

  Kids need calcium, vitamin D and diverse, load-bearing sport.

  Teenagers need about 1,000 mg of calcium daily; a 250 ml glass of milk has about 300 mg, so about 750 ml of milk or equivalent (yogurt, cheese) covers most of it. In Australia sun before 10 a.m. and after 2 p.m. can supply vitamin D without burning. Swimming and cycling don't load bone enough—a 1992 Stanford study of varsity athletes found gymnasts 'off the scale' while swimmers resembled sedentary controls, though it was observational.

• 05

  Vitamin D thresholds are debated.

  Beck cites 30 ng/mL as a common deficiency cutoff and 50 as sufficient, with some arguing for 75; she defers to others on specifics. Peter supplements 5,000 IU daily to stay around 50–60 ng/mL, admitting he has no clear indication beyond a hope of being better off later.

• 06

  Corticosteroids harm growing bones.

  Beck advises keeping children off steroid inhalers where possible or titrating to the lowest dose, and making sure kids who need them get ample milk, sun and loading.

• 07

  Inactivity rapidly causes anabolic resistance.

  In cast-immobilization studies, after two weeks the casted leg showed about 40–50% anabolic resistance versus the other leg—not aging, just disuse. Movement throughout life matters.

• 08

  DEXA T-scores and Z-scores mean different things.

  Osteoporosis is a hip T-score of −2.5 or lower (WHO), with −1 to −2.5 being osteopenia. A T-score compares you to an average 20–30-year-old of the same sex and race; a Z-score compares you to people your age—a Z of 0 is the 50th percentile, +1 about the 84th. Total hip is preferred over femoral neck because of analysis variability.

• 09

  LIFTMOR showed heavy lifting is safe and effective for women with low bone mass.

  About 100 postmenopausal women with low bone mass were randomized to high-intensity resistance and impact training—30 minutes twice weekly, four compound exercises (including deadlifts and squats) at about 85% of one-rep max, with jumping—or a low-intensity program, over eight months. Everyone had said their bones were too fragile; with expert coaching, it was safe.

• 10

  The results rival drugs.

  The training group gained a net benefit of a bit over 4% at the spine and about 6% at the femoral neck (controls lost about 2.5%). 3D hip analysis showed about a 13% net gain in femoral-neck cortical thickness. Function improved too: sit-to-stand, timed up-and-go, jumping, posture and grip strength.

• 11

  The WHI scare left a generation of women untreated.

  Peter calls the Women's Health Initiative's effect on hormone therapy one of the great tragedies of the past 25 years for bone health.

• 12

  Middle age is about preserving bone before the menopause cliff.

  For men and women in their 30s and 40s, Beck says most are on a plateau, so the goal is maintaining loading and avoiding the long sedentary stretches that drive loss. Women should build reserves before menopause. She acknowledges others may disagree given limited long-term data, but sees no downside to continued heavy, varied loading.